A curable composition has been improved in variously ways corresponding to the application, and has been widely used as a raw material for producing an optical part or a formed article, an adhesive, a coating material, and the like. For example, a curable composition that produces a cured product that exhibits excellent transparency is preferable as an optical part raw material or a coating material, and a curable composition that produces a cured product that exhibits high adhesion is preferable as an adhesive or a coating material.
In recent years, a curable composition has also been used as an optical device-securing composition (e.g., optical device-securing adhesive or optical device sealing material).
Examples of the optical device include a light-emitting device (e.g., laser (e.g., semiconductor laser diode (LD)) and light-emitting diode (LED)), a light-receiving device, a hybrid optical device, an optical integrated circuit, and the like. In recent years, an optical device that emits blue light or white light (i.e., has a shorter emission peak wavelength) has been developed, and widely used. There is a tendency in which the brightness of a light-emitting device having a short emission peak wavelength is significantly increased, and the amount of heat generated by such an optical device further increases.
Along with a recent increase in brightness of an optical device, a cured product of an optical device-securing composition may deteriorate due to exposure to high-energy light or high-temperature heat generated by the optical device, whereby cracking or delamination may occur.
Patent Documents 1 to 3 propose an optical device-securing composition that includes a polysilsesquioxane compound as the main component in order to solve the above problem.
A cured product obtained by curing the optical device-securing composition disclosed in Patent Documents 1 to 3 that includes a polysilsesquioxane compound as the main component may exhibit sufficient adhesion, but may exhibit insufficient heat resistance and insufficient transparency.
Patent Documents 4 and 5 respectively propose an epoxy resin composition that includes an alicyclic epoxy resin and an epoxy resin composition that includes a polythiol compound as an optical device sealing composition.
However, these compositions may show a deterioration in light resistance or adhesion with the passage of time.
Therefore, development of a curable composition that produces a cured product that exhibits better heat resistance and transparency, and also exhibits high adhesion has been desired.